feat(release): v0.4.0 foundations — ldflags version + goreleaser + CI Go 1.24

- Move version out of cmd/root.go hardcode into an ldflags-injected
  var. Makefile derives from 'git describe --tags --always --dirty';
  plain 'go build' / 'go run' get 'dev'. Release builds will get the
  tag via goreleaser.
- Add .goreleaser.yaml: multi-platform (linux/darwin/windows/freebsd ×
  amd64/arm64/arm) builds with SHA256 checksums, tar.gz/zip archives,
  forgejo release publishing. No GPG/S3 yet — deferred until a key is
  provisioned.
- Add .gitea/workflows/release.yml to run goreleaser on tag push.
  Uses built-in GITEA_TOKEN with override via RELEASE_TOKEN secret.
- Align CI Go version with go.mod (1.24). Previously CI ran 1.21,
  which would have silently missed any 1.22+ feature use.
- Move itchyny/gojq from indirect to direct (it's used in api.go).
  Drop stale x/sys v0.33.0 entry from go.sum.
- Ignore dist/ and bin/ in .gitignore.
- CHANGELOG: document v0.3.1 fix and Unreleased development changes.

Makefile

@@ -1,17 +1,23 @@
-.PHONY: help build run test clean lint lint-fix install
+.PHONY: help build run test clean lint lint-fix install release-snapshot release-check
+
+# Version derived from git tags; falls back to short SHA; appends -dirty if tree is modified.
+VERSION ?= $(shell git describe --tags --always --dirty 2>/dev/null || echo dev)
+LDFLAGS := -X 'forgejo.zerova.net/public/fgj-sid/cmd.version=$(VERSION)'
 
 help:
 	@echo "Available commands:"
-	@echo "  make build      - Build the application"
+	@echo "  make build      - Build the application (version: $(VERSION))"
 	@echo "  make install    - Install the binary to /usr/bin"
 	@echo "  make run        - Run the application"
 	@echo "  make test       - Run tests"
 	@echo "  make lint       - Run golangci-lint"
 	@echo "  make lint-fix   - Run golangci-lint with auto-fix"
 	@echo "  make clean      - Clean build artifacts"
+	@echo "  make release-snapshot - Build snapshot release artifacts via goreleaser"
+	@echo "  make release-check    - Validate .goreleaser.yaml"
 
 build:
-	go build -o bin/fgj .
+	go build -ldflags "$(LDFLAGS)" -o bin/fgj .
 
 install: build
 	install -Dm755 bin/fgj /usr/bin/fgj
@@ -29,5 +35,11 @@ lint-fix:
 	golangci-lint run --fix ./...
 
 clean:
-	rm -rf bin/
+	rm -rf bin/ dist/
 	go clean
+
+release-snapshot:
+	goreleaser release --snapshot --clean --skip=publish
+
+release-check:
+	goreleaser check